H.265/HEVC (High Efficiency Video Coding), hereinafter for brevity “HEVC”, has attracted much attention as the next-generation video coding standard. Compared to existing H.264/MPEG-4 AVC (Moving Picture Experts Group-phase 4 Advanced Video Coding) standard, HEVC provides almost double the compression performance. In HEVC, an adaptive filter called SAO (sample adaptive offset) is applied to improve the quality of decoded images.
As for technology related to adaptive filters, there is provided, for example, an image processing apparatus for calculating an offset value for color difference signals with respect to each divided region by referring to a quadtree structure and an offset value determined for a luminance signal supplied from an adaptive offset unit.
As for decoding techniques in HEVC, there is provided, for example, an image decoding apparatus for generating a predicted image of color difference signals either by making a directional prediction of the color difference signals or based on a correlation parameter indicating the correlation between a luminance signal and the color difference signals according to an intra prediction parameter of the color difference signals.
See, for example, Japanese Laid-open Patent Publication No. 2013-12845 and International Publication Pamphlet No. WO 2014163200
There are a plurality of setting items for the adaptive filters above, and in an encoding process, setting values for the individual items are encoded and set in encoded data. Thus, for encoded video data, information of the encoded setting values for a large number of items is configured. This contributes to an increase in the amount of encoded data.